Nowadays, personal communication devices have experienced great growth and are now rapidly gaining in popularity. The personal communication devices having image capturing devices are gradually marketable. The common image capturing devices are for example camera modules or video camera modules. When the image capturing devices are used in mobile phones, personal digital assistant (PDA) or notebook computers for video recording, video calling, video conferencing or other network applications, the convenience and the diversity of these image capturing devices are evident. Generally, such an image capturing device principally comprises a lens module, a lens holder, an image sensor and a printed circuit board (PCB). An example of the image sensor includes a CCD (charge coupled device) chip or a CMOS (complementary metal-oxide semiconductor) chip.
Conventionally, there are several methods of assembling the camera module. In accordance with a first assembling method, the image sensor is firstly fixed on the printed circuit board, a filter and a lens module are then combined with a lens holder, and the lens holder is finally glued on the printed circuit board. As such, a close space is defined by the printed circuit board, the lens holder and the filter. During the process of producing, transporting or assembling the camera module, some particles, dust or dirt (also referred as pollutant in this specification) may be brought into the lens module or the image sensor. Under this circumstance, the image quality of the image-capturing device is deteriorated. Generally, a testing process is performed to detect whether there is any pollutant present within the close space. Once any particle, dust or dirt is detected, the lens module needs to be detached from the printed circuit board in order to remove the particle, dust or dirt. Since the lens module has been fixed on the printed circuit board, the process of detaching the lens module from the printed circuit board may easily result in damage of lens module and even cause considerable economic loss. A related discussion is described in for example Taiwanese Utility Model Patent No. 283188, entitled “Assembling structure of lens module”. If there is a stain on the image sensor after the lens module has been glued on the printed circuit board, the lens module needs to be detached from the printed circuit board. This may leads to damage of the lens module and thus the lens module may fail to be used again. Under this circumstance, the manufacturing cost is increased. Therefore, there is a need of providing an improved fabricating method of the camera module.
In accordance with a second assembling method, the configurations of the camera module are similar to those made by the first assembling method. The lens module has a lens set and a lens barrel sheltering the lens set. After the camera module is assembled, the lens barrel of the lens module could be twisted out in order to perform a cleaning procedure. Although the cleaning procedure is simplified in comparison with the first assembling method, there are still some drawbacks. For example, after the cleaning procedure is completed, the lens barrel needs to be twisted in the lens holder again in order to recombine the lens barrel and the lens holder. During the lens barrel is twisted in the lens holder, particles are readily generated due to friction between the thread structures of the lens barrel and the lens holder. Once the particles fall into the internal portion of the camera module, a secondary pollution problem occurs and the image quality is also adversely affected. Under this circumstance, the yield of the camera module is still unsatisfactory.